1. Field of the Disclosure
The disclosure relates to a data center network system and a packet forwarding method.
2. Description of Related Art
Along with development of network technology, corporations widely use networks to provide services or exchange information. However, the cost for constructing and maintaining network equipments is considerable. Therefore, an operation mode of a network data center is gradually developed. The so-called network data center is referred to a large-scale data storage center, which can provide services such as host collocation, host rent, remote backup, and system and network management, etc. For example, after a corporation rent a host space or purchase a host collocation service from a network data center provider, the corporation can arbitrarily access and manage all information in their remote host space. Therefore, it is unnecessary for the corporation to construct a machine room for containing hardware or telecommunication equipments, instead, the corporation can place the related machines in the machine room owned by the network data center provider or rent the machines owned by the network center provider. In this way, the cost for network connection is reduced, and the labor cost for daily maintenance of the equipments is saved.
A most important part in operation of the network data center is to construct a structure of a data center network, so as to construct a large amount of virtual hosts to execute various services. Especially, in the data center network, the virtual hosts have to be easily migrated, and data packets have to be efficiently transmitted without causing a transmission loop. Therefore, it is an important issue for the related practitioner to design an efficient, liable and manageable network based on an economically reasonable design.
Ethernet is a trend of the current network structure, which has been widely applied in local area networks.
FIG. 1 is a diagram illustrating a network topology of an Ethernet structure used for a container computer of a network data center.
Referring to FIG. 1, the network can be divided into a core layer, a region layer and a top-of-rack (ToR) layer. The core layer includes 12 Ethernet switches, the region layer includes 12 Ethernet switches, and the ToR layer includes 48 Ethernet switches.
One container computer has 12 racks, and each rack has 4 ToR network switches. Moreover, each container includes 40 servers (i.e. physical machines), so that each of the container computers includes 480 servers. Assuming each of the servers operates 20 virtual machines, one container computer can provide 9600 virtual machines.
Although the Ethernet technology can be conveniently applied to the data center network, is has a problem of scalability. In detail, when a transmitter (for example, a virtual machine or a physical machine) on the Ethernet is about to send a data packet to a receiver (for example, a virtual machine or a physical machine) for communication, all of the network switches on a transmission path of the data packet between the transmitter and the receiver have to be stored with address information of the receiver, and such address information occupies a forwarding table entry in a forwarding table. However, the forwarding table configured in a commodity Ethernet switch can only record 16K-32K forwarding table entries, so that the Ethernet can only contain several hundreds to several thousands of the physical machines, generally.
FIG. 2 is an example of transmitting a data packet on the Ethernet.
Referring to FIG. 2, in the Ethernet, a physical machine A, a physical machine B and a physical machine C are connected through network switches SW1, SW2, SW3 and SW4 and communicate with each other by using network protocols on top of Ethernet. If virtual machines B1, B2 and B3 are run on the physical machine B, and the physical machine A forwards data packets to the virtual machines B1, B2 and B3 through a forwarding path P1 formed by the network switch SW1, the network switch SW2, the network switch SW3 and the physical machine B, forwarding tables of the network switch SW1, the network switch SW2 and the network switch SW3 have to be stored with address information of the virtual machines B1, B2 and B3, so that the data packets can be successfully forwarded to the virtual machines B1, B2 and B3 from the physical machine A. Therefore, in FIG. 2, if the forwarding table of the network switch SW1 can only store 16K forwarding table entries, the physical machine A can only communicate with 16K machines at most.
Accordingly, when constructing a mega data center, which hosts millions of virtual machines, about 110 container computers are required based on our design. Now, the Ethernet will not support communication of such large amount of the physical machines or the virtual machines.